468 THE HISTORY OF MEDIEVAL EUROPE and navy of his own rather than allow these foreigners to control all the trade of the land or have to depend on them for transportation when he wished to visit Germany or go to Palestine. Therefore the cities of Lombardy were sus- picious of Frederick's intentions when he summoned the feudal nobility of Germany to meet him at Cremona at Easter, 1226, to make arrangements for the crusade, and when he marched north from Apulia at the head of an armed force to meet them. Milan and her allies straightway formed a league and blocked the Alpine passes so that the Germans were unable to reach Cremona. The Lombard cities had been so independent since the death of Henry VI that now they were unwilling to observe even the terms of the Peace of Constance which they had forced from Bar- barossa. A few towns, however, looked eagerly to the emperor for aid against the others. The pope undertook to arbitrate between Frederick and the towns; but as he secured from them merely a promise First breach to su PP ress heresy and supply a few knights for with the the crusade, but no recognition of the impe- rial claims, Frederick was naturally dissatisfied. Honorius III (12 16-1227), however, who had directed Frederick's education, remained on friendly terms with his former pupil and perhaps was somewhat duped by Freder- ick's plausible promises and excuses and wily diplomacy. But now a more uncompromising pontiff and one less likely to have patience with Frederick succeeded to the Papacy as Gregory IX (1 227-1 241). When the emperor at last set sail from Sicily to the heel of Italy to put himself at the head of the assembled crusaders, a pestilence broke out in the army and Frederick himself was taken sick and accord- ingly postponed the expedition. But the pope refused to accept any excuse and excommunicated him. When Fred- erick, despite his excommunication, set sail for the East the next summer, the pope did what he could to render his expedition a failure. The Sultan, however, was having so much trouble with an obstreperous brother that he had no desire for war with Frederick. Therefore, although the latter
